The
gaps marked 1 were a tentative layout of extra air ports at the
base of the right firebox, and did make it into the final kiln (in
both fireboxes) but are not shown on the plans. These ports are
very occasionally used for stirring the embers, and once,
shamefully, to remove embers. Carol likes to mess about with the
ones at the chimney side, but I am inclined to think this is
unnecessary. If you have to remove embers then you are not
managing the fireboxes properly. However, if you fire this kiln
and are new to firing with wood you probably will mis-manage the
fireboxes at first, so these apertures might be a good idea.

The
brick marked 6 is where the mousehole for that firebox should be. The
wall between the fireboxes is marked 3.The chimney layout 2 is for
the top of the chimney. The bricks 5 are just there for the moment to
hold up the planned corbel arch 4. There are four of these corbel
arches leading from the fireboxes into the bagwall areas.

Why
use corbel arches instead of braced arches? There is no compelling
reasons to choose corbels, but a number of minor reasons. Firstly,
throat arches in salt kilns tend to collapse if the salt is
introduced near them, and for some good reasons that is where we like
to introduce the salt. I thought corbel arches would be easier to
repair. Secondly, if a braced arch was built here it would be
difficult to brace during the construction of the kiln, although it
could have been braced at the end of construction. Thirdly, I had
only a few arch bricks of the right sort of shape and I needed them
for the firebox doors. Fourthly, I had a number of silicon carbide
bricks garnered when the local sugar mill was demolished, and I did
not know where else to use them. They conduct heat readily, so are no
use on the outside wall, and this seemed a good place to put them, as
they are relatively resistant to heavy salting. They could not be
shaped, so could not be turned into arch bricks.